The Nahda party rejects Premier Hamadi Jebali's proposal after the killing of opposition figure Chokri Belaid spurred protests. A labor union calls for a general strike.

TUNIS, Tunisia — Tunisia's Islamist-led government Thursday rejected a proposal by its prime minister to form a new Cabinet amid growing political tension after nationwide protests sparked by the assassination of a key opposition figure.

The announcement by the dominant Nahda party highlighted differences among Islamists and spurred fresh uncertainty over how to keep the slaying of Chokri Belaid, a fierce government critic, from tipping the economically fragile country into deeper unrest.

Tunisia's main labor union heightened the pressure by calling for a one-day general strike to coincide with Belaid's funeral Friday. It was clear, however, that no prominent voice had a solution to quickly stem the worst crisis since the revolution two years ago that overthrew longtime autocrat Zine el Abidine ben Ali.

Much of the country was on edge on a rainy, cold Thursday. Stone-throwing protesters clashed briefly with security forces in Tunis, the capital. The most intense violence erupted in the phosphate mining city of Gafsa, where one person was reportedly killed as youths threw gasoline bombs at police firing tear gas.

The opposition supports Prime Minister Hamadi Jebali's proposal for a Cabinet of technocrats to run the country until new elections. But Nahda was unhappy with the suggestion, and reports indicated that some officials want Jebali, secretary-general of the organization, censured or possibly removed from the party.

"The prime minister did not ask the opinion of his party," Abdelhamid Jlazzi, Nahda's vice president, told the Tunisian news media. "We in Nahda believe Tunisia needs a political government now. We will continue discussions with other parties about forming a coalition government."

Political analyst Amine Mahfoud said this conflict will "tell us how much support Jebali has within Nahda."

"The country is now divided everywhere, even within Nahda," Mahfoud said. "The assassination on Wednesday marked a turning point in the history of Tunisia similar to the day in 2011 when Ben Ali fled the country."

The killing of Belaid by a gunman has sharpened the animosity between Islamists and secular liberals. No one has claimed responsibility for the death. But Belaid, a lawyer, often accused the moderate Nahda and ultraconservative Salafi Islamists of trying to turn Tunisia, long the most secular nation in the Arab world, into an Islamic state.

His slaying refocused attention on Nahda's inability to end bickering among political parties over government reforms and an assembly drafting a new constitution. Secularists worry that the charter would curtail civil freedoms.

The political infighting has not erupted into sustained deadly street protests such as those that have shaken Egypt's new Islamist-led government. But it has raised fears about the rise of radical Islamists in what has become in recent months an increasingly restive transition.

The atmosphere has been further strained by suggestions from politicians, journalists and a union leader that other opponents of the government may be targeted for assassination.

Such concerns are growing across the region. In Egypt, guards are protecting homes of opposition figures after a cleric issued an Islamic ruling, or fatwa, calling for the killing of political enemies of President Mohamed Morsi. One of them is Mohamed ElBaradei, a Nobel Peace Prize laureate, who leads the National Salvation Front, an opposition alliance.

"Regime silent as another fatwa gives license to kill opposition in the name of Islam," ElBaradei posted in a Twitter message. "Religion yet again used and abused."